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Linear Enamel Hypoplasia in the People of Ancient Jericho Ma#hewCapece1,JaimeUllinger2,SusanG.Sheridan3

1DepartmentofBiology,QuinnipiacUniversity2DepartmentofSociology,CriminalJusEce,andAnthropology,QuinnipiacUniversity

3DepartmentofAnthropology,UniversityofNotreDame

The analysis of general stress indicators is useful for assessing health of individuals during childhood. Linear enamel hypoplasias (LEH) are commonly examined due to the relative ease with which they can be recognized. LEH are defects that result from the early cessation of ameloblast cell activity (Duray, 1996), wherein enamel is laid down during childhood. While this process naturally slows as enamel placement progresses towards the end of the crown, it can be further disrupted by instances of malnutrition, disease, fever, and other stressors (Martin et al., 2007; Hasset, 2013). During physiological stress, the body diverts energy and resources away from less vital processes, such as enamel formation, in an effort to combat the effects of the stressor (Geber, 2014). While not every instance of stress results in the occurrence of LEH, when it does form, it presents as a defect in the pattern of enamel layering (Hassett, 2013). If examined properly, the results from LEH analysis can yield information about stressors that presented themselves during childhood (King et al., 2002). Defects on anterior teeth are readily visible due to the flat, smooth labial surfaces that are present (Hillson, 2014).

Anterior Teeth Canines Site Date LEH n % LEH n % Reference*

Jericho EBI 1 2 50.0 1 2 50.0 1 Jericho EBIV 13 21 61.9 6 12 50.0 1 Jericho MBA 7 27 25.9 6 20 30.0 1 Jericho Early Iron 1 1 100 1 1 100 1 Jericho Roman 1 1 100 1 1 100 1 Jericho All 23 52 44.2 15 36 41.7 1

Mendes, Egypt 3000 BCE – 395 CE 51 359 14.2 40 153 26.1 2

Trentino, Italy 2500 – 1800 BCE 73 88 83.0 31 35 88.6 3

C-Group Nubians, Sudan 2000 – 1600 BCE 11 103 10.7 7 58 12.1 4

Kerma, Sudan 1680 – 1550 BCE 14 51 27.5 10 32 31.3 4

Tombos, Sudan 1400 – 1050 BCE 17 95 17.9 9 49 18.4 4

Pella, Jordan 1100 – 900 BCE 55 112 49.1 35 48 72.9 5 Sa’ad, Jordan 560 – 650 CE 258 881 29.3 155 356 43.5 6

The examination of anterior teeth from Jericho revealed that 44.2% of all anterior teeth (n=52) exhibited at least one instance of LEH. Of the 36 canines displaying defects, 11.1% (n=4) had more than one occurrence of LEH. There was no significant difference in LEH frequency between the EBIV and MBA time periods (X2=4.9, df=2, p=0.01), with the Middle Bronze Age teeth exhibiting fewer defects (25.9%, compared to 61.9% in EB IV) (Figure 2). Teeth from EB IV Jericho were different from most of the comparative collections, except for those from Iron Age Pella (X2=0.7, df=2, p=0.2). Levels of LEH at Middle Bronze Age Jericho were similar to those found at Mendes (Fisher’s Exact p = 0.09), Kerma (X2=0.02, df=2, p=0.9), Tombos (X2=0.43, df=2, p=0.5), and Sa’ad (X2=0.03, df=2, p=0.9).

Background

Period Dates Early Bronze I (EBI) 3500-3100 BCE

Early Bronze IV (EBIV) 2300-2000 BCE

Middle Bronze (MBA) 2000-1550 BCE

Early Iron 1200-1000 BCE

Roman 63 BCE-134 CE

Materials and Methods

Polyvinylsiloxane molds (using Coltène-Whaledent’s Affinis) of canines (n=37) and incisors (n=16) from 46 individuals were made at the University of Cambridge’s Duckworth Laboratory. These molds were filled with an epoxy resin (Streuer’s EpoFix) to form replicas of the original teeth to be used for analysis. Casts were then coated in chromium using a sputter-coater at the Yale Institute for Nanotechnology and Quantum Engineering to allow for the examination of microstructures under microscopic analysis (Hubbard et al., 2009). Teeth exhibiting more than 80% of the original crown were visually examined with a Dino-Lite AD4113ZT digital microscope under ≥10x magnification for perikymata visibility (Hillson, 1992; Guatelli-Steinberg, 2003). Teeth were examined for LEH, presented as circumferential furrows on the surface of the tooth (Figures 2 and 3). This was confirmed by the presence of widely-spaced perikymata (occulusal wall of the stress episode) followed by more normally-spaced perikymata in the cervical wall (recovery) (Hubbard et al., 2009). Frequencies of LEH at Jericho were compared to a number of sites from the same region and/or time period, including one each from Egypt (Mendes) and Italy (Trentino), two from Jordan (Pella and Sa’ad), and three from Sudan (C-Group Nubians, Kerma, and Tombos) (Table 2). Statistical comparisons used chi-square tests with Yates’ correction for continuity and Fisher’s Exact Probability tests.

Discussion

*References: 1 = Current study; 2 = Lovell and Whyte 2002; 3 = Cucina 2002; 4 = Buzon, 2006; 5 = Griffin and Donlon 2009; 6 = El-Najjar, et al., 1996

The specimens examined for LEH defects come primarily from Early Bronze IV (2300-2000 BCE) and Middle Bronze Age (2000-1550 BCE) tombs at the ancient site of Jericho (Table 1; Figure 1). EBIV consisted of a non-urban occupation by nomads that led to more permanent settlements in the Middle Bronze Age that were built into a series of terraces on the slope of the mound in which the city was located (Kenyon, 1960; Kenyon, 1981). LEH will be examined to assess differences in health between the earlier EB IV and the later, more urban Middle Bronze Age.

TABLE 1. Time Periods at Jericho.

kilometers

N 0 50

Jerusalem

Jericho

Pella

Sa’ad

FIGURE 1. Map of the Southern Levant.

Results

FIGURE 2. Jericho P1 Skull W, Lower Left and Right Central Incisors, each with one defect.

FIGURE 3. Jericho A130, Lower Left Canine; no defect.

Jericho EB IV

Jericho MBA

Mendes Trentino C-Group Nubians

Kerma Tombos Pella Sa’ad

Χ2=4.9 p=0.01

p<0.01

p=0.04

p<0.01

Χ2=8.9 p<0.01

Χ2=0.7 p=0.2

Χ2=12.6 p<0.01

Χ2=6.1 p<0.01

FIGURE 4. Jericho EB IV LEH prevalence in anterior teeth compared to regional sites.

Jericho EB IV

Jericho MBA

Mendes Trentino C-Group Nubians

Kerma Tombos Pella Sa’ad

Χ2=4.9 p=0.01

p=0.09

Χ2=29.1 P<0.01

p=0.05

Χ2=0.03 p=0.9

Χ2=3.8 p=0.05

Χ2=0.43 p=0.5

Χ2=0.02 p=0.9

FIGURE 5. Jericho MBA LEH prevalence in anterior teeth compared to regional sites.

Acknowledgements: Dr. Michael Rooks and the Yale Institute for Nanoscience and Quantum Engineering; Drs. Deborah Clarke and Lani Keller, Dean Robert Smart and Associate Dean Allan Smits, Quinnipiac University; Dr. Marta Mirazón Lahr and Ms. Maggie Belatti, Duckworth Laboratory, University of Cambridge

Teeth from Early Bronze IV Jericho had more hypoplastic defects than those in the Middle Bronze Age, which may suggest that EB IV peoples were more physiologically stressed. Early Bronze IV is often discussed as a period of “social collapse” due to a failure to deal with changing climatic conditions (Rosen, 2007), before reorganization in the Middle Bronze Age. A drier climate contributed to lower agricultural yields (Rosen, 1995), which may in turn have caused widespread malnutrition and greater susceptibility to disease. Fewer general stress indicators in the Middle Bronze Age sample may reflect more access to adequate food resources by more members of the town of Jericho. The difference may also reflect differences in social status. However, samples from both time periods reflect a variety of tombs with varying status. Levels of LEH in EB IV Jericho are most similar to Iron Age Pella. Interestingly, researchers found little difference in LEH prevalence between Middle Bronze Age and Early Iron Age Pella (Griffin and Donlon, 2007), while people at MBA Jericho seemed to fare better than their contemporaries. Evidence suggested, however, that the MBA sample from Pella was primarily from individuals of lower social status. In general, MBA peoples were similar to samples from Nubia, which had evidence of relatively little stress (Buzon, 2006). Therefore, stress in MBA may have improved in the region in general (at least for higher-status individuals), and the “collapse” of Early Bronze IV may be reflected in greater physiological stress in the people of Jericho.

TABLE 2. LEH prevalence in canines and anterior teeth (combined).